Replace @timestamp with timestamp in my message - logstash

Elastic Stack Logstash
7

hi pjanzen,

This is my conf file

input {
            file{
        	path => "E:\softwares\logstash-6.5.4\bin\PA_FW_Traffic-2018-09-10.txt"
          start_position => beginning
         }
         }
        filter{
        mutate { 
        	remove_field => ["facility_label","facility","@version","priority","tags","host","timestamp","severity_label","severity","logsource"]
        	split => { "message" => "," }
         }
        grok {
            match => { "message" => ["^{timestamp}"] }
        	}

         date {
        		match => [ "timestamp", "yyyy-MM-dd :HH:mm:ss ZZZ" ]
        		target => "@timestamp"
        	}
         }
        output {
            stdout {}
            file {
                path => "E:/testmessage.txt"
         codec => line { format => ["%{@timestamp},%{message}"] } 	
        	}
        }